Infinitely variable transmissions are known for transmitting rotary motion from a rotary drive source to a rotary driven load such that the speed of rotation of the load may be selectively varied in a continuous and variable manner for a given rotary speed of the rotary drive source.
In use, such transmissions have a wide range of applications; for example such transmissions may be used in applications where the rotary drive source delivers a variable rotary drive such as in road vehicles wherein the transmission transmits rotational drive from an engine to the road wheels of the vehicle; alternatively such transmissions may be used in applications where the rotary drive source delivers a constant rotary drive such as in a machine tool lathe application wherein the transmission delivers a constant rotary drive from an electric motor to the chuck of the lathe.
Infinitely variable transmissions of the type disclosed in French patent application No. FR 0004842, published as FR2807811 (referred to throughout as such), are known wherein the transmission includes and epicyclic gear assembly having a rotary drive output for connection to a load to be driven and a rotary drive input for connection to a rotary drive source, the rotary drive input being arranged to drive the epicyclic gear assembly via first and second drive inputs driven by said rotary drive input, the first drive input being drivingly connected to said rotary drive input via a variator which is selectively operable to vary the relative rotational speeds of the first and second drive inputs and thereby cause a desired rotational change in said rotary drive outputs.
Infinitely variable transmissions of the type disclosed in FR2807811 tend to suffer from certain disadvantages. For example, the transmission is relatively complex and so is relatively expensive to produce. It is also generally bulky and requires a relatively large amount of occupancy space when installed in a drive system. Also the arrangement of components making up the variable transmission makes it difficult to easily change the drive ratios and/or torque transmission capabilities of the variable transmission when tailoring the variable transmission for a particular application.